Wear limiting adjustable brush means for a rotary drum encoder



March 31, 1970 p, 1 WAZNYS ET AL 3,504,146

WEAR LIMITING ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER Filed May28, 1968 2 Sheets-Sheet 1 fr 77 fz /f /05 7 :1r-:1111: /o Uf?, f ma n3 vn 4 /X/ Fwd Marh 31,`197`o v R'JMAVZNYS mL 3,504,146

WEAR LIMITIG ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER v FiledMay 2a, 1968 2 sheets-sheet 2 United States Patent O 3,504,146 WEARLIMITING ADJUSTABLE BRUSH MEANS FOR A ROTARY DRUM ENCODER Peter J.Waznys, Richmond Hill, N.Y., and John A.

Garrido, Englishtown, NJ., assignors to Collectron Corporation, NewYork, N.Y., a corporation of New York Filed May 28, 1968, Ser. No.732,581 Int. Cl. H01h 9/08 U.S. Cl. 200--166 7 Claims ABSTRACT OF THEDISCLOSURE This invention relates generally to the eld of rotary drumtype encoders of the class disclosed in our co-pending application, Ser.No. 660,252; filed Aug. 14, 1967, entitled Multi-Speed Encoder, andassigned to the same assignee as the instant application.

An object of the invention lies in the provision of an improved brushstructure in which the variation from an initial adjustment due to Wearof the contacting surfaces thereof is maintained at a minimum.

Yet another object of the invention lies in the provision of an improvedencoder of the class described, in which the individual brush elementsmay be conveniently replaced as required.

A further object of the invention lies in the provision of improvedencoder construction of the class described in which initial adjustmentof the component parts thereof, during assembly is materiallyfacilitated, as contrasted with prior art constructions.

A further object of the invention lies in the provision of an improvedencoder construction possessed of the above enumerated advantages, inwhich the cost ofl fabrication may be of a reasonable order, directlycomparable with existing prior art devices, thereby permittingconsequent wide sale, distribution and use.

These objects, as Well as other incidental ends and advantages, willmore fully appear during the progress of the following disclosure, andbe pointed out in the appended claims.

In the drawings, to which reference will be made in the specification,similar reference characters have been employed to designatecorresponding parts throughout the several views.

FIGURE 1 is a central longitudinal sectional view of an embodiment ofthe invention.

FIGURE 2 is a fragmentary plan view shown, one of the brush holding tabmembers comprising a part of the embodiment.

FIGURE 3 is a side elevational view of a tab element.

FIGURE 4 is a fragmentary end elevational view thereof, as seen from theplane 4 4 in FIGURE 3.

FIGURE 5 is a transverse sectional view as seen from the plane 5 5 inFIGURE 1.

FIGURE 6 is a fragmentary sectional View as seen from the plane 6 6 inFIGURE 1.

FIGURE 7 is a view in elevation as seen from the plane 7 7 in FIGURE 6,with an outer cover element removed for purposes of clarity.

In accordance with the invention, the device, gener- 3,504,146 PatentedMar. 31, 1970 lCC ally indicated by reference character 10 (FIGURE 1),comprises broadly: An outer casing element 11, a motion input shaftelement 12, a reduction element 13, a drum element 14, and a brushelement 15.

The outer casing 11 includes a primary shell 20 preferably formed as amachined casting, and including an end wall 21, a cylindrical wall 22,and a second end wall 23. Overlying the outer surface of the cylindricalwall 22 is a cover 24.

The end wall 21 is bounded by an outer surface 25, and an inner surface26, between which extend a pair of radially disposed bores 27 and 28which support pins 29 and 30, respectively for mounting in fixedrelation a part of the reduction element 13. A centrally disposed bore31 includes a counter bore portion 32 which forms a seat for a bearing33.

The cylindrical wall 22 includes an inner surface 35, and an outersurface 36 which supports a plurality of brush support elements 37 (seeFIGURES 6 and 7) between rst and second flange portions 39 and 40` whichsupport the cover 24, as is Well known in the art.

The end wall 23 is preferably formed as a separate piece, and includesan outer surface 43 and an inner surface 44. A recess 45 supports abearing 46 aligned with the bearing 33. An annular rabbet 47 permitsengagement with the free end of the cylindrical wall 22. A cylindricalprojection 48 supports lead wires 49 on an outer surface thereof, andprovides a threaded bore (not shown) by which the cover element 24 isattached by screw means.

The cover 24 may be formed as a metallic drawing, and includes an endwall member 54 and an integral cylindrical Wall member 55. The end wallmember includes an outer surface 56 and an inner surface 57, andincludes a plurality of openings 58 for passage of lead wires 49. Acentral opening 59 passes the screw 50 which engages in the abovementioned threaded bore in the cylindrical projection 48. Thecylindrical wall member 55 includes surface 61, and an inner surface 63which engages the flanges 39 and 40.

The 4motion input shaft element 12 includes a shaft member 66 supportedin bearings 33 and 46 and mounting a radially extending wave generatormember 67 having first and second lobes 68 and `69, each mounting abearing member as at 70l and 71. Inner bearing members 72 and 73 supportthe drum element 14 upon the shaft element 12 for relative rotationtherebetween.

The reduction element 13 eliminates the use of conventional gear trains,and includes a flexible spline -member 76 cooperating with a iixedspline member 77. The flexible spline members 76 is formed of resilientsynthetic resinous material, and is bounded by a smooth inner surface 79and a toothed outer surface 80 adapted to engage the toothed innersurface 81 of the fixed Spline member 77 Openings 83l and -84 engage thepins 29 and 30 to x the spline member 77 with respect to the casingelement 11.

The operation of the reduction element will be best understood from theconsideration of FIGURE 5, wherein with rotation ofthe shaft element 12,the wave generating lobes v68 and 69 will progressively deform theflexible spline member 76 as it engages the fixed spline member 77, andwith each revolution of the shaft member 66, the drum element 14 whichmounts the flexible spline member 76 will rotate an angular distanceequivalent to the difference in the number of teeth on the members 77and 76 as compared with the number of teeth on the fixed spline member.

The drum element 14 is generally similar to that disclosed in the abovementioned co-pending application, Ser. No. 660,252; and includes a coremember 87 forming a central bore 88 for the engagement of the shaftmember 66, and locking means 89 for fixing the core 87 upon the shaft,which structure is both disclosed and claimed in said application. Theouter surface 96 of the core member 87 is cylindrical in configuration,and mounts an insulative sleeve 91 which in turn mounts electricallyconductive rings 92.

The brus'h element 15 includes a plurality of arcuately shaped generallyrectangular support Imembers 94 which are mounted on the outer surfaceof the cylindrical wall 22. As best seen in FIGURES 1 and 6, the innersurface 96 thereof is provided with an arcuately shaped tongue 97engaging a correspondingly shaped slot 98- in the wall 22,

whereby the former is adjustable through an arcuate path v of motionwith respect to the latter. Cementitious means 99 engages a slot 100,preferably extending over an arcuate distance of approximately degrees.An opening 101 provides for the projection of a conductive brushstructure, which bears upon the conductive rings 92. A

plurality of channel forming members 103 define a plurality ofinterstices 104, each one accommodating a wiper tab assembly 105(FIGURES 2 and 3). The assemblies 105 are substantially Similar, eachincluding a thin metal interface 106 bounded by an upper surface |107, alower .f

The wiper blades 116, are identical in construction,

and as will more fully appear, are adapted to maintain an initialadjustment within Very close limits, irrespective of the amount of wearoccurring upon the surface in direct ,contact with the drum element 14.As best seen in the above figures, each wiper blade is formed from asingle length of wire, and includes a iirst member 117, a first endsegment 118 thereof being Welded to the interface 106. The segment 118is interconnected by a bent portion to an angularly disposed portion120, in turn connected by a right angle bend to an upwardly facing loopportion 121 which lies in a plane substantially perpendicular to thesurface of the drum element 14 which it contacts, which plane isperpendicular to the direction of surface movement at that point. Theopposite end of the loop -121 is connected by a right angle bend 122 toan angularly disposed portion 123 parallel to the portion 120, in turnconnected through a bend portion 124 and welded segment 124a. Thesegment 124a connects with a small 180 degree loop 125 to a member 126which is substantially identical to the rst member 117, and whichterminates in a second end 127. The member 126 includes a secondupwardly facing loop 128 lying in a plane coplanar with that of the loop121.

With continued use, wear will occur on the loops 121 and 128. This wearwill occur on the lower surfaces of the loops which are in tangentialcontact with the drum element, but from a consideration of FIGURES 4 and6, it will be apparent that at no point can the total wear cause acontact width greater than the dia-meter of the wire from which thewiper blade is made, and with increased wear, `as the theoretical pointcontact enlarges to an ovoid surface, the pressure is distributed over agreater area, so that continued use results in ever lessening wear.

We wish it to be understood that We do not consider the inventionlimited to the precise details of structure shown and set forth in. thisspecification, for obvious modifications will occur to those skilled inthe art to which the invention pertains,

We claim; i

1. Improved brush block construction for use with a shaft-driven encoderhaving an outer housing and an electrically conductive drum arranged forrotation therein, said housing having openings therein for thepenetration of bnush means therethrough to contact said drum, saidconstruction comprising: an arcuately-shaped support member of generallyrectangular conguration and having a first surface including anarcuately-shaped tongue extending .outwardly thereof, there being anarcuatelyshaped slot disposed in an outer surface of said housing,whereby said support member is rectilinearly adjustable along an arcuatepath with respect to said housing; said support memer including aplurality of channel-,forming members defining a plurality ofinterstices therebetween, and a plurality of wiper tab assembliesslidably positioned within said interstices; whereby said support membermay be slidably adjustable with respect to said housing, and said wipertab assemblies may be individually adjustable with respect to each otherupon said support member.

2. Structure in accordance with claim 1, in which the wiper tabassemblies are retained in position by frictional means.

3. Structure in accordance with claim 1, including Cementitious meansfor retaining said tab assemblies in given adjustment.

4. In a combination current-conducting brush and a contacting conductivesurface in relatively movable relation thereto along a principal axis ofmovement, said brush being formed of resiliently deformable round wire,and having means for supporting said wire substantially at one endthereof, the improvement comprising: said wire including a flexiblesegment having a first relatively fixed end, and a second relativelyfree end: said flexible segment having a principal axis substantiallyparallel to said principal axis of movement, said free end forming alooped segment lying in a plane, said plane interconnecting saidprincipal axis of movement substantially at a right angle, whereby whensaid looped segment executes relative movement with respect to saidconductive surface, the elfect of maximum possible wear on said loopedsegment is limited to the shifting of the contactl point along saidprincipal axis of movement to a degree equal to the radius of across-section of said wire.

5. Structure in accordance with claim 4, said brush constructionincluding a pair of flexible segments, each fixed at one end thereof,and each interconnecting one end of said loop segment.

6. Structure in accordance with claim 5, including a plurality of pairsof flexible segments, each pair interconnecting a looped segment.

7. Structure in accordance with claim 6, in which said looped segmentslie in a common plane.

References Cited UNITED STATES PATENTS 1,399,492 12/ 1921 Krantz.

2,401,419 6/1946 Ford.

2,454,788 11/1948 Frese.

2,723,319 11/1955 Sebring et al. 20G-25 2,853,563 9/1958 Bole et al.200-8 3,243,529 3/ 1966 Behringer.

FOREIGN PATENTS 1,261,331 12/1961 France.

ROBERT K. SCHAEFER, `Primary Examiner ROBERT A. VANDERHYE, AssistantExaminer Us. 01. XR.

